Are there real benefits to be gained from switching to synthetic oil = MPG imporvement, reduced engine wear, etc. If so, when's the best time to make the switch - at the first oil change after a suitable break-in period? Is their any one synthetic brand that's better than others or are they all about the same?
I just did my first oil change in the Prius over the weekend at 3,000 miles. First oil change is important because the engine is still in break in period and you want to remove very small machine shavings, etc. early. You can switch to synthetic at any time. Went with Mobil 1 5W-30. Be careful not to use 4 qts or you can overfill. I run Mobil 1 synthetic in all my cars and not necessarily for improved viscosity which I believe is true, but also to be able to go longer between changes. If you plan on changing the oil periodically at the same mileage intervals as using regular oil, then the advantages of synthetic oil are diminished and it is not cost effective. Instead of changing every 3K, I usually go with between 4,500 to 5,000 miles between changes.
Summarizing from tons o' previous threads: Synthetics are most helpful under harsh conditions. Because of the way it is started and because it is not running about half the time the Prius engine probably enjoys the gentlest operating environment of any engine on the road, so the benefits of synthetic should be minimal. (Nevertheless to amuse myself with the thought that I am using the least possible amount of petroleum I will be using synthetic oil.) Some brands (Mobil 1, etc.) are entirely synthetic. Others are only partly synthetic. Read the label. The owner's manual says to wait for the first scheduled maintenance to switch to synthetic. It also advises for mysterious reasons not to switch back and forth between natural and synthetic. Whatever you do, use the recommended weight 5W-30 and the recommended grade or better (uhh, I don't have that page handy). The recommended interval in US/Canada is 6 months/5k miles regardless of type of oil. The Europe/Japan interval is longer, perhaps because of assumed differences in driving patterns. Note that there is no need whatsoever to fiddle with fractional quarts of oil. Put in exactly three quarts and you will fill the system (including filter) almost exactly midway between the "FILL" and "ADD" marks. (Gee, it's almost like Toyota planned it that way :_>) This is ideal for convenience and for ease of avoiding both over- and under-filling. Both of those conditions are bad for the engine.
For my Prius 2010, can I get away with using regular oil at 5000mi intervals instead of synthetic at 10,000 mi intervals?
You're better off asking this question in a Gen III forum. You can, but it's not recommended, and the "savings" of 2x the oil changes don't really balance out all things considered.
I've been using synthetic blend the last few changes. They had a good special on it at the auto parts store (Castrol). I'm pretty sure the engine ran a little more quietly but maybe it was just in my head. I haven't noticed any gain in MPG over conventional oil.
I would stay away from blends too. You just diminish the benefits of the synthetic. This is just marketing tool used to sell inferior oil at higher prices. It's the same as a drug dealer cutting their product to increase volume and make more money.
First has anyone sent in an oil analysis of fossil oil compared to full synthetic ? Second has anyone observed the inner engine of one using fossil oil compared to full synthetic. I have been told and we all know about being told, by a trusted engine mechanic two things. You should see the inside of an engine that used full synthetic for life vs fossil oil and " I can tell you if you usually use cheap gas or top tier". I always thought B.S. to that. Another reason again i was told for using synthetic is anti sludge which has been a problem for chrysler and Toyota in some of their engines. I know people with muscle cars that swear by synthetic oil and Top Tier gas but i really don't know. I just stick with works for me synthetic in every engine i own none have had any failures and none need added oil between changes.
For the non-mechanic, take off the valve cover or oil pan from an engine with synthetic and conventional oils and you will see. The benifits are far more reaching though and well documented. I am a Mechanic.
As far as MPG gain, this can be gotten by purchasing synthetic high mileage formula (eg Mobil 1 advanced fuel economy). As far as synthetic vs. conventional, cost is closer these days. I remember 35 years ago when Mobil-1 was $5 and conventional was what, 50-cents? You had to be a real fan or car fanatic then, now synthetic seems great bargain to me, especially on sale or Walmart 5-qt bottles.
I took my 2014 Toyota Prius II for an oil change. The oil change guy said he can put synthetic blend. After the oil change, I look at the window sticker he placed on the windshield, and it says 10W-30, with the next oil change in 3000 miles. I don't think 10W-30 is even a synthetic blend. The car calls for full synthetic 0W-20. It's the first time my car has gotten anything other than 0W-20. My question is, would 10W-30 oil damage my car, when it calls for 0W-20 synthetic oil??? Thanks.
